Nicad Battery Help
 

I have a 1100 mhA Nicad 4 cell Rx pack that was bought and cycled about 15 months ago. After a full charge and discharging at C\5 (.22A) and a 1v/cell cutoff, it showed a capacity of 1,048. I just cycled it again today and it read 974. This is about 7% drop. First - is it normal for the battery to come in under its rated capacity on initial cycle ? And second, is this 7% drop acceptable and normal for this age battery ? I use an Ace Digipulse charger to charge all my batteries. Its about a 15 hour charge , then I discharge on a Rip Max charger/discharger.
Thanks in advance for your help ............

RE: Nicad Battery Help
 

It's been a while since I've used a nicad pack, but as I recall, if the pack is new, it will take several charge/discharge cycles to get the pack up to full capacity. Check out this info:

http://www.onlybatterypacks.com/up/p...STRUCTIONS.pdf

It appears to be good info on nicad maintenance.

Jesse

RE: Nicad Battery Help
 

I think you should cycle it three times and take the average. Plus he is right about the new cells, it may take a couple of good cycles up and down to break in the pack. Its norm to take them down to about 1.1 v per cell. and then try and peek charge them.

good luck with them

sticks

RE: Nicad Battery Help
 

Planer1,
You are in good shape, you are getting more than 80% of rating.
Yeas, it can vary that much between charges.
There are a lot of variables in the process.

Additionally, I like to discharge to .9 volts.

The multiple cycles is a substitution for a forming charge.
This is a C/10 charge for about 16 hours.
This must be done with a non-peaking charger.
A wal-wart is a good choice for this.
This is known more as a necessity with NiMh than NiCd.
However, their chemistry and procedures are much the same.

Myself, I prefer NiCd over NiMh.
The reason is the NiMh will self discharge at a faster rate than NiCd.
I've heard about 5% per day. 20 days = dead.
This then necessitates the forming charge to get things running properly again.
Just to much work and hassle for me.

There is a Battery forum here on RCU, lots of good info.
Check it out.

Good Luck,
KW_Counter

RE: Nicad Battery Help
 

Nicads really don't require much more a 1/10c charge for 16 hours, or untill slightly warm, and go fly. the only real reason for cycling is to check cond. I suspect your introducing some error into the eqation by manually having to switch between charge and discharge as well as using a peak charger. Nicads are not considered completely discharged untill .8v so it sounds like your battery is just fine. The best insurance is a loaded volt meter before each flight. Stop flying if it drops below 4.8v or 6V depending if your running a 4 or 5 cell pack. For added insurance, batteries should be changed out every 2-3 years or monitored more closely. I personnally don't let my batteries get to old and use a loaded volt meter and never had a failure, (knock on wood). I never fast charge either.

RE: Nicad Battery Help
 

Here are four good sources of info on batteries, the last two covering primarily NiCads.
The first one having very good info on all types of batteries.
http://www.rcbatteryclinic.com
http://www.whenshtf.com/showthread.php?t=2153
http://www.srbatteries.com/nimh.htm
http://dansdata.com/gz011.htm
http://users.frii.com/dlc/battery.htm

RE: Nicad Battery Help
 

For an accurate reading you also need to discharge it at a specific rate otherwise your numbers will be slightly off. I forget what the rate is, but maybe someone else knows? Is it C/5?

RE: Nicad Battery Help
 

I thank everyone for your help. Appears this battery is in better shape than another 1100 I just bought last week. I have cycled it twice now at the same settings (.22A -1v/cell) and the first cycle came in at 711 and the second 815. Any chance of this new pack continuing to increase with another cycle or two ?
Thank again ..............

RE: Nicad Battery Help
 

You are correct, C/5 and you need to drop down to 0.9 volts/cell during the discharge if you are comparing capacity to factory specs. If you discharge at a higher rate or only down to 1 or 1.1volts/cell you will get a lower number of MAH's.

RE: Nicad Battery Help
 

Yes. Also, your discharge circuitry may be cutting off to early. If the lowest voltage at the end of discharge is not down to 0.9 volts/cell you will get a lower MAH reading than the factory specs indicate.

RE: Nicad Battery Help
 

Not only is the discharge circuit cutting off prematurely, the charge circuit may be doing the same if it is peak detecting. I am using a Hobbycity Accucell-6 and had fits with it when I first tried to charge and cycle my Nicd's and Nimh battts, the Peak detect voltage was set too low.
Curtis

RE: Nicad Battery Help
 

I'm sure one of the reasons I'm getting below factory ratings on my discharge is the fact that I'm only using a cut off of 1 volt per cell. I want to continue at this setting until I have this first group of cycles done, so I can get a good comparitive set of readings from the same settings. Mid year, I will start with the .9 volts/cell and see what I get. I have never cycled my batteries in that I'v read where peak charging is actually hard on the packs, thus my choice to use the Ace Digipulse for charging. Takes 15 hours to get it done, but I'm not stressing the pack and its the way I'v always done it so far. May go with the Hobbico Accu-cycle Elite charger and begin cycling on it next time around. I like the fact that it does two batteries at the same time, plus it has its own AC/DC power pack.
Thanks for your responses guys ...........